UI: Add (eRTMP) multitrack video output

[palana]

Note that this PR includes a bunch of merges from currently open PRs and a FIXME commit to help with testing, which will go away as soon as the dependency PRs are merged

Description

This implements multitrack video support for Twitch Enhanced Broadcasting and Amazon IVS Multitrack Video

Motivation and Context

Multitrack video/Enhanced Broadcasting allows sending multiple video tracks/renditions from the users machine, resulting in generally higher quality renditions at lower bitrates compared to single track streaming with server side transcoding, since e.g. losses roundtripping frames through another decode/encode step are removed.
Enhanced Broadcasting/multitrack video uses server side configuration to provide easier onboarding for users, and balanced values for the number of renditions and their bitrates.

How Has This Been Tested?

This has been tested in the Twitch Enhanced Broadcasting beta

Types of changes

• New feature (non-breaking change which adds functionality)

Checklist:

• My code has been run through clang-format.
• I have read the contributing document.
• My code is not on the master branch.
• The code has been tested.
• All commit messages are properly formatted and commits squashed where appropriate.
• I have included updates to all appropriate documentation.

[tytan652]

This feature is clearly not implemented in a future-proof way, it tangles even more service behavior in the UI that should be plugin-ified (with APIs).

Continuously shoehorning service integrations was already a mistake, and this PR goes to the same wrong direction rather than trying to go to a better direction.

[RytoEX]

Rebased first. Now pushing cleanups:

1. The multitrack audio commits don't actually need to be in here because the later commits don't touch the same code. VOD Track just won't work without them, but removing the commits reduces some noise here.
2. We can drop "UI: Keep weak stream output ref in status bar" since it was handled in UI: Keep weak stream output ref in status bar #10680.

[palana]

@RytoEX, @Warchamp7: moved the remaining service settings into groupboxes after #10633 (comment)

[RytoEX]

Started a review a while back and forgot to submit it. Submitting it now so get this one feedback item raised.

[RytoEX]

I tried to autosquash locally, but it looks like some of the autosquash commits are trying to apply changes to commits before the actual base changes the autosquash commits try to fixup. Could you squash the commits?

Per @Warchamp7 , the UI itself is okay. @Lain-B and I are still doing code review.

[palana]

I tried to autosquash locally, but it looks like some of the autosquash commits are trying to apply changes to commits before the actual base changes the autosquash commits try to fixup. Could you squash the commits?

Per @Warchamp7 , the UI itself is okay. @Lain-B and I are still doing code review.

@RytoEX: commits are squashed, apologies for the unclean fixup commits

[Lain-B]

Thanks for rebasing. There are a few minor things, such as Linux/macOS just not being implemented at all and failing with "GPU not supported", but generally it has my approval. We'll probably just have to ifdef out the Linux/macOS codepath for it and disable it for the time being but otherwise again it generally has my approval.

[RytoEX]

Rebased to latest master. May push trivial fixes (text nits + minor cleanups or just text nits) before merging.

[koolscooby]

Thanks for rebasing. There are a few minor things, such as Linux/macOS just not being implemented at all and failing with "GPU not supported", but generally it has my approval. We'll probably just have to ifdef out the Linux/macOS codepath for it and disable it for the time being but otherwise again it generally has my approval.

If possible, we'd like to keep the implementation as-is so we can release server-side updates to start vending ladders for Linux, MacOS, AMD AMF, and Intel QSV without requiring additional changes to OBS.

In the short term, we can improve the error message that is shown so that it makes it more apparent to users that the reason it is unsupported is not the build of OBS Studio, but instead the service that vends the configuration.

[RytoEX]

Leaving a brief review comment for posterity.

[RytoEX]

The CI failures are unrelated. The GitHub Actions Ubuntu runners are restarting due to some issue related to apt packages that indicate they require service restarts.